Also we have learned from law enforcement sources — law enforcement officials — that the FBI is now investigating, and this is an ongoing investigation, into Paula Broadwell.

... The FBI investigation is seeing whether she had improper access to General Petraeus' emails and may have had access to his ... may have accidentally or deliberately had access to classified information. And so we know this investigation is taking place, and that it has identified Paula Broadwell.

Kessler's report claims that the FBI intercepted Petraeus' emails with Broadwell, and they had included sexually explicit references, like "sex under a desk." The pair reportedly broke up some point after Petraeus become CIA Director, but he continued sending thousands of emails to her over the past few months.

The FBI had been investigating an unrelated and much broader case before stumbling on the affair. Fox News has learned that during the course of this investigation, the name of journalist and Petraeus biographer Paula Broadwell came up. The FBI followed that lead and in doing so, uncovered his affair with her. The FBI for some time was concerned that perhaps Petraeus was some sort of victim, but there has been no evidence discovered to back up such concerns.